Stentriever devices for removing an occlusive clot from a vessel and methods thereof

ABSTRACT

Devices described herein include a stentriever for removing an occlusive clot. The stentriever can include a membrane cover on the proximal end which can be sized to form a seal with the tip of an intermediate catheter. Clot engagement sections and/or a distal engagement section of the stentriever can also include a full or partial membrane covering to control the direction of aspiration and/or areas where the aspiration applies suction to the thrombus or clot. The membranes can be used to direct the aspiration so as to pull the clot deeper into the clot engagement sections of the stentriever, thereby improving grip on the clot. The design can also increase the effectiveness of clot fragment protection for friable clots by providing pores and/or clot cells in a distal engagement section.

FIELD OF INVENTION

The present disclosure generally relates to devices intended for removing acute blockages from blood vessels, and more particularly, to stentriever devices with membranes to direct fluid aspiration and enhance the stentriever's grip on an occlusive clot.

BACKGROUND

There are significant challenges associated with designing clot removal devices that can deliver high levels of performance. One challenge stems from the nature of the vasculature around an occlusive clot, which is often fragile and delicate. Neurovascular vessels, for example, are more fragile than similarly sized vessels in other parts of the body. Applying excessive tensile forces to these vessels could result in perforations and hemorrhage. Another challenge stems from the wide range of morphologies and consistencies of occlusive clots. Long strands of softer clot material may tend to lodge at bifurcations or trifurcations, resulting in multiple vessels being simultaneously occluded over significant lengths. More mature and organized clot material is likely to be less compressible than softer, fresher clot material, and under the action of blood pressure it may distend the compliant vessel in which the clot is lodged.

Stent-like clot retrievers, otherwise known as stentrievers, are being increasingly used to remove clots, as the devices show promise in dealing with some of the challenges described above. Stentrievers are self-expanding devices, similar in appearance to a stent attached to the end of a long shaft, which are advanced through a microcatheter and deployed across clot obstructions in order to trap and retrieve the clot. Many stentrievers rely on a pinning mechanisms to grab the clot by trapping the clot between the self-expanding, stent-like body and the vessel wall. Current stentrievers have a number of disadvantages that decrease the utility of the devices.

One disadvantage is that many stentrievers rely exclusively on an outward radial force (RF) to retain a grip on the clot. If the RF is too low the stentriever may lose its grip on the clot, but if the RF is too high the stentriever may damage the vessel wall and/or may require excessive force to withdraw the stentriever from the vessel. Stentrievers that apply sufficient RF to deal with all clot types may cause vessel trauma and serious patient injury, and stentrievers that apply low RF to remain atraumatic may not effectively handle all clot types.

Another disadvantage with current stentrievers is with the pinning mechanism itself. Stentrievers that rely exclusively on pinning clots against a vessel wall may not restrain the clot effectively when passing a branch vessel or when passing into a vessel that is larger than the fully expanded diameter of the stentriever. These and other disadvantages exist with previous stentriever devices. Accordingly, there is an ongoing need for an improved stentriever device that can improve grip on an occlusive clop without increasing the outward RF on the clot, thereby protecting the surrounding vasculature.

SUMMARY

Examples presented herein include stentrievers with membranes to direct fluid aspiration and enhance the stentriever's grip on an occlusive clot. The stentriever design described herein can include a membrane cover on the proximal end which can be sized to form a seal with the tip of an intermediate catheter. Clot engagement sections and/or a distal engagement section of the stentriever can also include a full or partial membrane covering to control the direction of aspiration and/or areas where the aspiration applies suction to the thrombus or clot. The membranes can be used to direct the aspiration so as to pull the clot deeper into the clot engagement sections of the stentriever, thereby improving grip on the clot. The design can also increase the effectiveness of clot fragment protection for friable clots by providing pores and/or clot cells in a distal engagement section.

An example stentriever can include a shaft extending between a proximal end and a distal end. A first expandable clot engagement section can extend from the shaft. The stentriever can include a proximal flow channel that is positioned proximal to the first expandable clot engagement section. The proximal flow channel can include a membrane covering to direct an aspiration from the first expandable clot engagement section and through the proximal flow channel. The stentriever can comprise a collapsed configuration to be inserted into a microcatheter and include an expanded configuration for exerting an outward radial force on an occlusive clot.

The first expandable clot engagement section can include a first clot inlet to capture the clot. The first clot inlet can be positioned on the stentriever distal to the first expandable clot engagement section.

The proximal flow channel can include a collapsed configuration to be inserted into a microcatheter, and the proximal flow channel can include an expanded configuration to exert an outward radial force on an intermediate catheter. In the expanded configuration, the proximal flow membrane can engage with an inner surface of the intermediate catheter at a proximal seal area do direct aspiration flow.

The first expandable clot engagement section can include a first clot engagement membrane directing the aspiration into the first expandable clot engagement section.

The stentriever can include a second expandable clot engagement section that extends from the shaft. The second expandable clot engagement section can be positioned distal to the first expandable clot engagement section.

The second expandable clot engagement section can include a second clot engagement membrane to direct the aspiration into the second expandable clot engagement section.

The second expandable clot engagement section can include a second clot inlet to capture the clot. The second clot inlet can be positioned on the stentriever distal to the second expandable clot engagement section.

The stentriever can include an intermediate flow channel positioned proximal to and adjacent the second expandable clot engagement section. The intermediate flow channel can direct the aspiration from the second expandable clot engagement section to the first expandable clot engagement section.

The stentriever can include a distal engagement section positioned distal to the first expandable clot engagement section. The distal engagement section can extend from the shaft. The distal engagement section can include a plurality of distal clot cells to capture clot fragments, such that the clot fragments do not pass distal to the stentriever.

The distal engagement section can include a distal membrane. The distal membrane can include distal pores that can constrict the flow of aspiration into the distal engagement section. The constriction of aspirate flow through the distal engagement section can create a negative pressure around the first and/or second expandable clot engagement sections to further pull the clot into the engagement sections.

The first expandable clot engagement section can further include a first clot inlet capturing the clot. A distal membrane can constrict flow from the distal engagement section to the proximal flow channel to create a negative pressure at the first expandable clot engagement section, thereby pulling the clot into the first clot inlet.

An example system for removing a clot from a vessel can include a stentriever. The stentriever can include a shaft extending between a proximal end and a distal end. The stentriever can include a first expandable clot engagement section extending from the shaft. The stentriever can include a proximal flow channel positioned proximal to and adjacent the first expandable clot engagement section. The proximal flow channel can include a proximal flow membrane. The system can further include an intermediate catheter. The stentriever can have a collapsed configuration to be inserted into a microcatheter, and the stentriever can have an expanded configuration to expand in a vessel. In the expanded configuration, the proximal flow cannel can exert a radial force on the intermediate catheter, and the proximal flow membrane can seal against the inner surface of the intermediate catheter. The aspiration can be directed from the first expandable clot engagement section, through the proximal flow channel, and into the intermediate catheter.

The first expandable clot engagement section can include a first clot inlet to capture a clot within the vessel.

The first expandable clot engagement section can include a first clot engagement membrane. The first clot engagement membrane can direct an aspiration into the first expandable clot engagement section.

The stentriever can further include a second expandable clot engagement section extending from the shaft. The second expandable clot engagement section can be positioned distal to the first expandable clot engagement section. The second expandable clot engagement section can further include a second clot inlet for capturing the clot.

The stentriever can further include an intermediate flow channel positioned proximal to and adjacent the second expandable clot engagement section. The intermediate flow channel can direct the aspiration from the second expandable clot engagement section to the first expandable clot engagement section.

The second expandable clot engagement section can include a second clot engagement membrane directing the aspiration into the second expandable clot engagement section.

The stentriever can include a distal engagement section positioned distal to the first expandable clot engagement section and extending from the shaft.

The distal engagement section can include a plurality of distal clot cells for capturing clot fragments.

The distal engagement section can include a distal membrane. The distal membrane can include distal pores that constrict flow of the aspiration into the distal engagement section. The constriction of aspirate flow through the distal engagement section can create a negative pressure around the first and/or section expandable clot engagement sections to further pull the clot into the engagement sections.

The distal membrane can include distal flow aperture directing the aspiration into the distal engagement section. The distal flow aperture can be a partial opening in the distal engagement section that constricts a flow of the aspirate into the distal engagement section. The constriction of aspirate flow through the distal engagement section can create a negative pressure around the first and/or section expandable clot engagement sections to further pull the clot into the engagement sections.

An example method for removing a clot from a vessel can include delivering a stentriever into the vessel and across the clot. The stentriever can include a shaft extending between a proximal end and a distal end. The stentriever can include an expandable clot engagement section extending from the shaft. The expandable clot engagement section can include a clot engagement membrane for directing a fluid into the expandable clot engagement section and a clot inlet. The stentriever can include a proximal flow channel positioned proximal to and adjacent the expandable clot engagement section. The proximal flow channel can include a proximal flow membrane. The proximal flow membrane can direct the fluid from the expandable clot engagement section and to the proximal flow channel. The method can include expanding the stentriever so that the expandable clot engagement section expands and exerts a radial force on the clot to engage the clot. The method can include advancing an intermediate catheter into the vessel and to the proximal flow channel. The proximal flow membrane can seal to an inner surface of the intermediate catheter. The method can include applying aspiration to the intermediate catheter such that a flow of the fluid is directed by the clot engagement membrane and into the proximal flow channel to capture the clot in the clot inlet. The method can include pulling the stentriever proximally to remove the clot from the vessel.

The stentriever can include a distal engagement section positioned distal to the expandable clot engagement section and extending from the shaft. The distal engagement section can include a distal membrane with a plurality of distal pores. The method can further include constricting, via the distal membrane, the flow of the fluid through the plurality of distal pores and into the distal engagement section. The constriction of the fluid flow can create a negative pressure to pull the clot into the clot inlet.

The distal engagement section can include a plurality of distal clot cells. The method can include preventing, via the plurality of distal clot cells, at least some clot fragments from passing distal to the stentriever.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and further aspects of this invention are further discussed with reference to the following description in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating principles of the invention. The figures depict one or more implementations of the inventive devices, by way of example only, not by way of limitation.

FIG. 1 is a side-view illustration of an exemplary stentriever, according to aspects of the present invention;

FIG. 2 is a side-view illustration of an exemplary stentriever interacting with an intermediate catheter, according to aspects of the present invention;

FIG. 3 is a side-view illustration of an exemplary stentriever having an intermediate flow channel, according to aspects of the present invention;

FIG. 4 is a top-view illustration of an exemplary stentriever, according to aspects of the present invention;

FIG. 5A is a side-view illustration of an exemplary stentriever having an inner channel, according to aspects of the present invention;

FIG. 5B is a side-view illustration of an exemplary inner channel, according to aspects of the present invention;

FIG. 6 is a perspective-view illustration of an exemplary stentriever with a full-length inner channel, according to aspects of the present invention;

FIG. 7A is a side-view illustration of an exemplary frame for a stentriever, according to aspects of the present invention;

FIG. 7B is a top-view illustration of the exemplary frame for a stentriever depicted in FIG. 7A, according to aspects of the present invention;

FIG. 8 is an end view of a partially-open distal engagement section, according to aspects of the present invention;

FIGS. 9A-91 depict an exemplary method of deploying a stentriever and removing an occlusive clot from a vessel, according to aspects of the present invention; FIG. 9A depicts a clot occluding a vessel; FIG. 9B a depicts a guide wire fed through the vessel and across the clot 10; FIG. 9C depicts a stentriever advanced through the microcatheter distal to the clot;

FIG. 9D depicts the microcatheter retracted proximally while the position of the stentriever is maintained; FIG. 9E depicts an intermediate catheter advanced to a proximal flow channel of the stentriever; FIG. 9F depicts aspiration being applied to the proximal flow channel via the intermediate catheter; FIG. 9G depicts a flow of the aspirate into the stentriever; FIG. 9H depicts the stentriever partially retracted into the intermediate catheter; and FIG. 9I depicts the stentriever retracted into the intermediate;

FIG. 10A is a flowchart depicting a method of removing a clot from a vessel, according to aspects of the present invention;

FIG. 10B is a flowchart depicting a method of using a distal engagement section to constrict flow and prevent clot fragments from passing distal to the stentriever, according to aspects of the present invention;

FIG. 11 is a flowchart depicting a method of deploying a stentriever, according to aspects of the present invention;

FIG. 12A is a flowchart depicting a method of removing a clot from a patient, according to aspects of the present invention; and

FIG. 12B is a flowchart depicting a method of removing a clot from a patient, according to aspects of the present invention.

DETAILED DESCRIPTION

Aspects of the present invention relate to a stentriever that includes a full or partial membrane cover on the proximal end of the device that is sized so that the proximal section can form a seal with the tip of an intermediate catheter. The stentriever device can include one or more expandable clot engagement sections and/or a distal engagement section. The expandable clot engagement sections and the distal engagement section can also include a membrane covering to control the direction of aspirate, and thus the direction of suction upon a thrombus or clot. The direction of aspirate can act to pull a clot deeper into inlet windows (i.e., clot inlets) of the expandable clot engagement sections. The direction of aspirate and suction can improve clot grip, decrease dislodgement of a clot within the stentriever, and increase retention of the clot when the clot is pulled into the intermediate catheter, access or guide catheter, or access sheath. In some examples, the design can also increase the effectiveness of clot-fragment protection for friable clots by providing antegrade flow through the distal engagement section.

Turning to the figures, FIG. 1 is a side-view illustration of an exemplary stentriever 100, according to aspects of the present invention. In some examples, this expanded configuration is exemplary of a stentriever 100 that is deployed into vessel. In some examples, a stentriever 100 can include a first expandable clot engagement section 102. The first expandable clot engagement section 102 can be an expandable feature that has a collapsed configuration and an expanded configuration, the expanded configuration being shown in FIG. 1 . In a collapsed configuration, the first expandable clot engagement section 102 can be inserted into a microcatheter for deployment into a vessel and across a clot. It is contemplated that a diameter 103 of a first expandable clot engagement section 102 can be less than approximately 1.75 mm when the first expandable clot engagement section 102 is in a collapsed configuration. For example, ordinary microcatheters can have inner diameters of from 0.015 inches to 0.065 inches (approximately 0.38 mm to approximately 1.65 mm), and it is contemplated that a diameter 103 of a first expandable clot engagement section 102 can fall within these typical ranges. In the expanded configuration, the first expandable clot engagement section 102 can open to engage a clot within vessel by exerting a radial force upon the clot. A first expandable clot engagement section 102 can be manufactured according to the size of the vasculature in which the stentriever 100 is being deployed. It is contemplated that the diameter 103 of the expanded first expandable clot engagement section 102 can range from approximately 1.5 mm to approximately 7.0 mm, for example, and not limitation, approximately 4.00 mm. As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±20% of the recited value, e.g. “about 90%” may refer to the range of values from 71% to 99%.

The first expandable clot engagement section 102 can be made from a material capable of recovering its shape automatically once unsheathed into its expanded configuration. The material could be in many forms such as wire, strip, sheet, or tube. In some examples, the first expandable clot engagement section 102 can include, but is not limited to, Nitinol, stainless steel, MP35N, tungsten, and/or the like or any combination or alloy thereof. In some examples, the material can be made from a memory shape material, such as Nitinol, and the expanded configuration for a first expandable clot engagement section 102 can be made by heat setting the material to the expanded configuration.

In some examples, a stentriever 100 can include a first clot engagement membrane 104 attached to the first expandable clot engagement section 102. The first clot engagement membrane 104 can be a full or partial covering of the first expandable clot engagement section 102 to direct a suction and/or aspirate into the first expandable clot engagement section 102. The material for the first clot engagement membrane 104 can include silicon, polyurethane, polypropylene, polyethersulfone, and/or the like. In some examples, the material for the first clot engagement membrane 104 can be pliable such that the material can be opened as the first expandable clot engagement section 102 opens from a collapsed configuration to an expanded configuration.

A first expandable clot engagement section 102 can include a first clot inlet 106. A first clot inlet 106 can be an opening distal to the first expandable clot engagement section 102 that is not covered by a first clot engagement membrane 104 and provides an area for an occlusive clot to be pulled into the first expandable clot engagement section 102. As will be appreciated, the examples described herein provide a way to capture a clot without relying exclusively on the radial force applied by the expandable sections of the stentriever 100. As suction is applied to the stentriever 100, the clot can be directed along with the flow of aspirate into the first clot inlet 106 via the first clot engagement membrane 104, and continued suction can provide improved grip on the clot.

A stentriever 100 can include a proximal flow channel 108. The proximal flow channel 108 can be positioned proximal to the first expandable clot engagement section 102. The proximal flow channel 108 can have a collapsed configuration and an expanded configuration, similar to the first expandable clot engagement section 102 described above. It is contemplated that the diameter 109 of a proximal flow channel 108 in a collapsed configuration can, similar to the first expandable clot engagement section 102, be less than approximately 1.75 mm so as to fit within a microcatheter for delivery into the vessel.

The proximal flow channel 108 can be a braided tube, laser cut metallic tube, laser cut polymeric tube and/or the like. In some examples, the proximal flow channel 108 can include, but is not limited to, materials such as Nitinol, stainless steel, MP35N, tungsten, and/or the like or any combination or alloy thereof. In some examples, the material can be made from a memory shape material, such as Nitinol, and the expanded configuration for a proximal flow channel 108 can be made by heat setting the material to the expanded configuration.

The proximal flow channel 108 can include a proximal flow membrane 110. The proximal flow membrane 110 can cover an outer surface of the proximal flow channel 108 at a position proximal to the first expandable clot engagement section 102. The proximal flow membrane 110 can direct the flow of aspirate from the first expandable clot engagement section 102 and through the proximal flow channel 108. The flow of the aspirate through the proximal flow channel 108 can increase the suction around the first expandable clot engagement section 102 so as to pull a clot deeper into first clot inlet 106. The material for the proximal flow membrane 110 can be silicon, polyurethane, polypropylene, polyethersulfone, and/or the like. In some examples, the material for the proximal flow membrane 110 can be pliable such that the material can be opened as the proximal flow channel 108 opens from a collapsed configuration to an expanded configuration.

In some examples, the proximal flow channel 108 can be opened into its expanded configuration while deployed into the vessel. Once expanded, the proximal flow channel 108 can have a diameter 109 of approximately equal to the inner diameter of an intermediate or access catheter. For example, once deployed, an intermediate catheter can be advanced into position after the stentriever 100 is deployed within a clot. The intermediate catheter can be directed to the proximal flow channel 108. In some examples, the proximal flow membrane 110 can form a seal with the inner surface of the intermediate catheter. The seal can allow aspiration to be drawn from the first expandable clot engagement section 102, through the membrane-covered proximal flow channel 108, and into the intermediate catheter to further pull the clot into the first clot inlet 106. Intermediate catheters can have an inner diameter of approximately 0.040 inches to approximately 0.120 inches (approximately 1.0 mm to approximately 3.0 mm). Accordingly, it is contemplated that the diameter 109 of a proximal flow channel 108 in an expanded configuration can fall within those ranges.

The proximal flow channel 108 can have a length suitable for engaging with an intermediate catheter which has been forwarded to the vicinity of the clot. In another embodiment, the proximal flow channel can have sufficient length to engage with an intermediate or access catheter which has been parked in the Internal Carotid Artery. It is contemplated that the length of the proximal channel can have a range of approximately 2.0 mm to 100 mm.

A stentriever 100 can include a flexible shaft 112. The shaft 112 can act as a both a delivery mechanism to feed the stentriever 100 into the vessel and as a scaffold or frame for the additional features of the stentriever 100. The expandable clot engagement sections (e.g., first expandable clot engagement section 102) for example, can be connected to and extend from the shaft 112. The shaft can be made from a flexible material, including but not limited to metals and polymers, such that the stentriever 100 can bend as the device is deployed into a vessel.

A stentriever 100 can include a second expandable clot engagement section 114. The second expandable clot engagement section 114 can extend from the shaft 112, similar to the first expandable clot engagement section 102, and be positioned distal to the first expandable clot engagement section 102 on the shaft 112. The second expandable clot engagement section 114 can be similar in all aspects to the first expandable clot engagement section 102. Though the first expandable clot engagement section 102 and second expandable clot engagement section 114 can comprise identical materials and have identical dimension, nothing requires the two sections to be identical. The second expandable clot engagement section 114 can act as a second capturing device, wherein in an expanded configuration, the second expandable clot engagement section 114 can engage the clot within vessel by exerting a radial force upon the clot. Although FIG. 1 depicts a stentriever 100 having two clot engagement section (i.e., first expandable clot engagement section 102 and second expandable clot engagement section 114), a stentriever 100 described herein is not limited to two clot engagement sections, as more than two could be provided.

In some examples, a stentriever 100 can include a second clot engagement membrane 116 attached to the second expandable clot engagement section 114. The second clot engagement membrane 116 can be a full or partial covering of the second expandable clot engagement section 114 to direct a suction and/or aspirate into the second expandable clot engagement section 114. The material for the second clot engagement membrane 116 can be similar to the materials described above for the first clot engagement membrane 104.

A second expandable clot engagement section 114 can include a second clot inlet 118. A second clot inlet 118 can be an opening distal to the second expandable clot engagement section 114 that is not covered by a second clot engagement membrane 116 and provides an area for an occlusive clot to be pulled into the second expandable clot engagement section 114. By providing a first clot inlet 106 and a second clot inlet 118, the clot can be pulled, by providing aspiration to the proximal flow channel 108, into both clot inlets 106,118 for improved grip on the clot.

A shaft 112 of a stentriever 100 can include a distal tip 120. The distal tip 120 can include a rounded and/or smooth end so as to not perforate a wall of a vessel as the stentriever 100 is being deployed within the vessel. In some examples, the distal tip 120 can include radiopaque coil or marker disposed on or in the distal tip 120 for visibility under fluoroscopy. Additional radiopaque coils or markers can be added near the expandable clot engagement sections such that a physician can view the position of the device in relation to the occlusive clot under fluoroscopy.

A stentriever 100 can include a distal engagement section 202 positioned distal to the first expandable clot engagement section 102; when a stentriever 100 includes a second expandable clot engagement section 114, the distal engagement section 202 is distal to the second section. When a physician inserts the stentriever 100 into a vessel, the stentriever 100 can be passed beyond the clot such that the distal engagement section 202 is within the vessel distal to the clot. The distal engagement section 202 can have a collapsed configuration and an expanded configuration, and the dimensions of the distal engagement section 202 in the collapsed configuration and the expanded configuration can be similar to the dimensions described above for the first expandable clot engagement section 102. As will be described below, once expanded, the distal engagement section 202 can expand to fill the cross-sectional area of the vessel and constrict fluid flow through the distal engagement section 202. The materials that can be used for a distal engagement section 202 can include, but are not limited to, Nitinol, stainless steel, MP35N, tungsten, and/or the like or any combination or alloy thereof. In some examples, the material can be made from a memory shape material, such as Nitinol, and the expanded configuration for a distal engagement section 202 can be made by heat setting the material to the expanded configuration.

A distal engagement section 202 can include a distal membrane 204. The distal membrane 204 can be a partial membrane covering of the distal end of the distal engagement section 202. The material for the distal membrane 204 can be silicon, polyurethane, polypropylene, polyethersulfone, and/or the like.

The distal membrane 204 can include one or more distal pores 206. Distal pores 206 can be holes created in the distal membrane 204 to allow flow, albeit limited flow, through the distal membrane 204. The distal pores 206 can be laser cut, stamped, or perforated holes within the material of the distal membrane 204. At least a portion of the distal pores 206 can have a length of less than 500 micrometers from one side of the distal pore 206 to the other. In the case that the distal pores 206 are circular, the circular distal pores 206 can have a diameter of less than 500 micrometers. The length and/or diameter of the distal pores 206 can be altered so as to increase or decrease the amount of flow permitted through the distal pores 206. For example, distal pores 206 can constrict (i.e., partially limit but not necessarily completely restrict) flow of aspirate through the distal engagement section 202. When suction is applied to the proximal flow channel 108 via an intermediate catheter, the constricted flow through the distal pores 206 can create an area of negative pressure between the distal engagement section 202 and the first expandable clot engagement section 102. This negative pressure can increase the suction of the clot into the first clot inlet 106, thereby improving grip on the clot. When a stentriever 100 includes a second expandable clot engagement section 114, the negative pressure provided by the constricted flow can also further pull the clot into a second clot inlet 118.

In some examples, the distal pores 206 can also serve to prevent friable-clot fragments from passing distal to the stentriever 100. As described above, clots are oftentimes fragile and delicate. When a clot is being removed from a vessel, fragments of the clot can dislodge from the body of the occlusion. The distal pores 206 provide a mechanism for preventing the loose fragments from passing distal to the stentriever 100 as the clot and device are removed from the vessel.

A distal engagement section 202 can include a plurality of distal clot cells 208 positioned proximal to the distal membrane 204. The distal clot cells 208 can be part of the frame of the distal engagement section 202. For example, the distal engagement section 202 can be a braided mesh of the materials described above, and the distal clot cells 208 can be the areas between the scaffold of the braided mesh. When the stentriever 100 is removed from the vessel, the distal clot cells 208 can help to grip the clot and prevent the clot from moving distal to the stentriever. The distal clot cells 208 can also provide a mechanism for preventing loose fragments of the clot from passing distal to the stentriever 100 as the clot and device are removed from the vessel.

FIG. 2 is a side-view illustration of an exemplary stentriever 100 interacting with an intermediate catheter 300, according to aspects of the present invention. FIG. 2 depicts an exemplary intermediate catheter 300 being positioned at a proximal flow channel 108, as described above. The intermediate catheter 300 can form a seal with the proximal flow membrane 110 at a proximal seal area 302, thereby allowing suction to be directed from the first expandable clot engagement section 102, into the proximal flow channel 108, and through the intermediate catheter 300. The intermediate catheter 300 can be advanced over the shaft 112, and the proximal end of the shaft 112 can reside within the intermediate catheter 300 when the catheter is proximate the proximal flow channel 108.

FIG. 3 is a side-view illustration of an exemplary stentriever 100 having an intermediate flow channel 402, according to aspects of the present invention. A stentriever 100 can include an intermediate flow channel 402 positioned proximal to and adjacent the second expandable clot engagement section 114. The intermediate flow channel 402 can have a collapsed configuration and an expanded configuration, similar to the configurations described above for the proximal flow channel 108. The dimensions of an intermediate flow channel 402 can also be similar to the dimensions of a proximal flow channel 108. The intermediate flow channel can be a braided tube, laser cut metallic tube, laser cut polymeric tube and/or the like. In some examples, the intermediate flow channel 402 can include, but is not limited to, materials such as Nitinol, stainless steel, MP35N, tungsten, and/or the like or any combination or alloy thereof. In some examples, the material can be made from a memory shape material, such as Nitinol, and the expanded configuration for an intermediate flow channel 402 can be made by heat setting the material to the expanded configuration.

An intermediate flow channel 402 can include a membrane, similar to the proximal flow membrane 110 described above for the proximal flow channel 108. The intermediate flow channel 402 can direct a flow of aspirate from the second expandable clot engagement section 114 to a position proximal to the second expandable clot engagement section 114. The flow of the aspirate through the intermediate flow channel 402 can be used to localize the suction upon the clot. For example, an intermediate flow channel 402 can allow the aspirate suction to be directed to the second clot inlet 118, further improving the grip on the clot. In some examples, a certain amount of open space can be disposed between the proximal end of the intermediate flow channel 402 and the first clot inlet 106 (as shown in the figure) such that the first clot inlet 106 has room to capture at least a portion of the clot.

FIG. 4 is a top-view illustration of an exemplary stentriever 100, according to aspects of the present invention. This view of a stentriever 100 provides an alternative view of the stentriever 100 shown in FIG. 1 . As can be seen, the first clot inlet 106 (and the second clot inlet 118, when provided) can remain open and without a membrane covering. This allows the clot to enter the uncovered area and be captured within the inlets.

FIG. 5A is a side-view illustration of an exemplary stentriever 100 having an inner channel 404, according to aspects of the present invention. In some examples, a stentriever 100 can include an inner channel 404 that extends from the proximal end of the device to the distal engagement section 202. FIG. 5A depicts an exemplary stentriever 100 without membranes on the first expandable clot engagement section 102, the second expandable clot engagement section 114, or the distal engagement section 202. The absence of the membranes in the view provides an unobstructed view of an exemplary inner channel 404. An inner channel 404 can have a collapsed configuration and an expanded configuration, similar to the configurations described above for the proximal flow channel 108. An inner channel 404 can, in some examples, be an extension of the proximal flow channel 108. In these examples, the proximal flow channel 108—inner channel 404 combination can extend from the area proximal to the first expandable clot engagement section 102 to the distal engagement section 202. The proximal flow channel 108 can include a membrane (e.g., proximal flow membrane 110) extending to the first clot inlet 106 to help direct the aspirate and/or suction, as described herein.

FIG. 5B is a side-view illustration of an exemplary inner channel 404, according to aspects of the present invention. This view shows an exemplary inner channel 404 without the expandable sections for contacting a clot, and thus provides a detailed view of the inner channel 404. An inner channel 404 can be a braided tube, laser cut metallic tube, laser cut polymeric tube and/or the like. In some examples, the inner channel 404 can include, but is not limited to, materials such as Nitinol, stainless steel, MP35N, tungsten, and/or the like or any combination or alloy thereof. In some examples, the material can be made from a memory shape material, such as Nitinol, and the expanded configuration for an inner channel 404 can be made by heat setting the material to the expanded configuration.

The inner channel 404 can include inner channel membranes 406 at positions along the length of the inner channel 404. The inner channel membranes 406 can be made similar materials as those described for the proximal flow membrane 110 above. The inner channel membranes 406 can be positioned at locations on the length of the inner channel 404 to correspond with the one or more clot engagement sections described above. For example, an inner channel membrane 406 can be positioned proximate a second expandable clot engagement section 114 (not shown in the figure) such that aspirate can be directed from the second expandable clot engagement section 114, into the inner channel membrane 406, and proximal in the device. In some examples, an inner channel membrane 406 can be provided proximate the distal engagement section 202 (not shown in the figure) to direct flow from the distal engagement section 202.

In some examples, the inner channel 404 can include a plurality of inner channel pores 408 within the surface of the inner channel 404. The inner channel pores 408 can be openings that allow fluid to flow from an area outside of the inner channel 404 to an area inside the inner channel 404. The inner channel pores 408 can extend from the proximal flow membrane 110 to the end of the inner channel 404; in examples with one or more inner channel membranes 406, the inner channel pores 408 can reside in areas not covered with membrane material. In some examples, the inner channel pores 408 can be cut, etched, drilled, or the like into the surface of the inner channel 404. In other examples, the inner channel pores 408 can be inherent features of the inner channel 404 material. For example, if an inner channel 404 is a braided tube or the like, the inner channel pores 408 can be the area between the braids of the material. The inner channel pores 408 can serve to prevent large clot fragments from entering the inner channel 404, thereby preventing the stentriever 100 from clogging. Clogging of the proximal end of the stentriever 100 could degrade the suction described herein that improves the grip on the clot. It is contemplated that the inner channel pores 408 can have a length and/or diameter (depending on the shape of the particular inner channel pore 408) that is from approximately 200 micrometers to approximately 1.50 mm (e.g., from approximately 200 micrometers to approximately 500 micrometers; from approximately 500 micrometers to approximately 800 micrometers; from approximately 800 micrometers to approximately 1.20 mm; or from approximately 1.20 mm to approximately 1.50 mm). These dimensions can prevent large clot fragments from entering the inner channel 404 and clogging the suction but can also allow small fragments to be aspirated and removed from the area (e.g., through the proximal flow channel 108 and intermediate catheter 300).

FIG. 6 is a perspective-view illustration of an exemplary stentriever 100 with a full-length inner channel 404, according to aspects of the present invention. The exemplary stentriever 100 in FIG. 6 shows that the examples shown in FIGS. 1-5A are merely exemplary and are not inclusive of all designs contemplated herein. In some examples, a stentriever 100 can include an inner channel 404 that extends from the proximal flow channel 108 to the distal engagement section 202. It is also contemplated that an inner channel 404 can extend only partially across the length of the device, for example only to a second expandable clot engagement section 114 (or a third section, etc.). FIG. 6 also shows an example stentriever 100 wherein only the proximal flow channel 108 includes a membrane (i.e., proximal flow membrane 110), while the remainder of the length of the inner channel 404 does not include a membrane, which is in accordance with some examples.

FIGS. 7A and 7B are illustrations of an exemplary frame 504 for a stentriever, according to aspects of the present invention. In some examples, the expandable clot engagement sections (i.e., first expandable clot engagement section 102, second expandable clot engagement section 114, distal engagement section 202, etc.) can be attached to a frame 504. The frame 504 can be attached to and extend from the shaft 112, as shown in FIG. 7B, to create the expanded construct described herein. In some examples, a full-length or partial-length inner channel 404 (e.g., the inner channel shown in FIG. 5B) can be provided to extend along the length of the shaft 112 and inside the frame 504. The frame 504 can include any of the features described herein.

In some examples, the distal end of the distal engagement section 202 can, in lieu of distal pores 206 (as shown in FIGS. 1-4 ), include a distal flow aperture 502. The distal flow aperture 502 can be an area of the distal engagement section 202 that is not covered with distal membrane 204 so as to constrict the flow of aspirate through the distal engagement section 202.

FIG. 8 is an end view of a partially-open distal engagement section 202, according to aspects of the present invention. As described above, the constriction of flow through the distal engagement section 202 can create a negative pressure proximal to the distal engagement section 202, thereby increasing the grip on the clot. The distal flow apertures 502 can be partial openings in the distal membrane 204 that allows a limited amount of fluid flow through the distal membrane 204.

FIGS. 9A-9F depict an exemplary method of deploying a stentriever 100 and removing an occlusive clot 10 from a vessel 12, according to aspects of the present invention. FIG. 9A shows a clot 10 occluding a vessel 12. In FIG. 9B, a guide wire 602 can be fed through the vessel 12 and across the clot 10. A microcatheter 600 can then be advanced over the guide wire 602 and distal to the clot 10. The guide wire 602 can then be removed from within the cannulated microcatheter 600.

As shown in FIG. 9C, the stentriever 100 can be advanced through the microcatheter 600 in its collapsed configuration until the distal tip 120 of the device reaches the distal end of the microcatheter 600. As shown in FIG. 9D, the microcatheter 600 can then be retracted proximally while the position of the stentriever 100 is maintained. Upon retracting the microcatheter 600, the stentriever 100 can be unsheathed to allow the stentriever 100 to expand into its expanded configuration. In FIG. 9D, only the distal engagement section 202 has been unsheathed.

As shown in FIG. 9E, once the stentriever 100 is unsheathed and fully expanded, an intermediate catheter 300 can be advanced, for example over the microcatheter and/or along the shaft of the stentriever 100, to the proximal flow channel 108. As described above, the proximal flow channel 108 can include a membrane that allows the intermediate catheter to form a seal against the proximal flow channel 108.

As shown in FIGS. 9F and 9G, aspiration can be applied to the intermediate catheter 300. The flow of fluid 16 can be directed by the membrane-covered first expandable clot engagement section 102 (and second expandable clot engagement section 114, as shown in the figure), to pull the clot 10 into the engagement sections. The distal engagement section 202 can include distal pores 206 or distal flow apertures 502, as described herein, to constrict the flow of fluid 16 through the distal engagement section 202. The constricted flow 604 of fluid 16 through the distal engagement section 202 can create a negative pressure area 606 near the expandable clot engagement sections 102,114, which can facilitate pulling the clots into the sections 102,114.

As shown in FIG. 9H, once suction is applied to the proximal flow channel 108 and the clot 10 has been sufficiently captured, the clot 10 can be pulled into the intermediate catheter 300 to be removed from the vessel 12. The position of the intermediate catheter 300 can be maintained, and continued aspiration can be provided to aspirate any clot fragments 14 that may have migrated distal to the stentriever 100, as shown in FIG. 9I. In some examples, the intermediate catheter 300 can be removed along with the stentriever 100 and clot 10 as a single unit through a guide or access catheter.

FIGS. 10A-12B are flow diagrams illustrating methods of removing an occlusive clot with a stentriever. These method steps can be implemented by any of the example means described herein or by similar means, as will be appreciated.

Referring to method 1000 as outlined in FIG. 10A, in step 1010, a stentriever can be delivered into a vessel and across a clot. The stentriever can include a shaft extending between a proximal end and a distal end. An expandable clot engagement section can extend from the shaft. The expandable clot engagement section can include a clot engagement membrane directing a fluid into the engagement section. A clot inlet can be provided in the engagement section for capturing a clot. The stentriever can also include a proximal flow channel with a proximal flow membrane, as described herein. In step 1020, the stentriever can be unsheathed, for example from an access sheath or a microcatheter, to expand the stentriever. Upon expansion of the stentriever, the expandable clot engagement section can engage the clot. In step 1030, an intermediate catheter can be advanced into the vessel and to the proximal flow channel of the stentriever. As described herein, the inner surface of the intermediate catheter can create a seal with the proximal flow membrane. In step 1040, aspiration can be applied to the intermediate catheter such that a flow of fluid is directed by the clot engagement membrane into and into the proximal flow channel to pull the clot into the clot inlet. In step 1050, the stentriever can be pulled proximally to remove the clot from the vessel.

The method 1000 illustrated in FIG. 10A can further include one or more of the steps outlined in FIG. 10B. Referring to method 1060 as outlined in FIG. 10B, in step 1070, the flow of aspiration at the clot engagement section can be constricted by distal pores of a distal engagement section. The constriction of the flow can create a negative pressure near the clot engagement section to pull the clot into the clot inlet. In step 1080, friable-clot fragments can be prevented from passing distal to the stentriever by a plurality of distal clot cells in the distal engagement section and/or the distal pores of the distal engagement section.

The methods 1000 and 1060 as illustrated in FIGS. 10A and 10B can further include one or more of the steps outlined in FIG. 11 . Referring to method 1100 as outlined in FIG. 11 , in step 1110, a guide wire can be delivered across an occlusive clot. In step 1120, a microcatheter can be advanced along the guide wire and across the clot 10. In step 1130, the guide wire can be removed from the microcatheter, leaving the microcatheter in place within the vessel. In step 1140, a stentriever, as described herein, can be advanced through the microcatheter in a collapsed configuration. In step 1150, the microcatheter can be pulled proximal (i.e., retracted) to allow the stentriever to expand into an expanded configuration, thereby exerting an outward radial force on the clot.

The methods 1000, 1060, and 1100, as illustrated in FIGS. 10A-11 can further include one or more of the steps outlined in FIG. 12A. Referring to method 1200 a as outlined in FIG. 12A, in step 1210, the clot can be captured within the stentriever (i.e., within a clot inlet of the stentriever), and the stentriever and the clot can be pulled into the intermediate catheter. In step 1220, the stentriever and captured clot can be removed from the intermediate catheter, leaving the intermediate catheter in place. In step 1230, with the intermediate catheter in place within the vessel, suction can be provided to the intermediate catheter to aspirate any remaining clot fragments in the vessel.

As an alternative to the steps provided in method 1200 a as outlined in FIG. 12A, one or more of the steps outlined in FIG. 12B can be performed. Referring to method 1200 b, in step 1240, the clot can be captured within the stentriever (i.e., within a clot inlet of the stentriever), and the stentriever and the clot can be pulled into the intermediate catheter. In step 1250, the stentriever, clot, and intermediate catheter can be removed via a guide catheter or an access sheath.

The descriptions contained herein are examples of embodiments of the invention and are not intended in any way to limit the scope of the invention. As described herein, the invention contemplates many variations and modifications of the stentriever device including using alternative geometries of structural elements, combining shapes and structural elements from various example embodiments, using alternative materials, etc. These modifications would be apparent to those having ordinary skill in the art to which this invention relates and are intended to be within the scope of the claims which follow. 

The invention claimed is:
 1. A stentriever for removing a clot from a vessel, comprising: a shaft extending between a proximal end and a distal end; a first expandable clot engagement section directly connected to and extending from the shaft and comprising a first clot engagement membrane directing an aspiration into the first expandable clot engagement section; a second expandable clot engagement section extending from the shaft and positioned distal to the first expandable clot engagement section; an intermediate flow channel positioned proximal to and adjacent the second expandable clot engagement section; a proximal flow channel positioned proximal to and adjacent the first expandable clot engagement section, the proximal flow channel comprising a proximal flow membrane directing the aspiration from the first expandable clot engagement section and to the proximal flow channel; and a distal engagement section positioned distal to the first expandable clot engagement section and extending from the shaft, wherein the stentriever comprises a collapsed configuration to be inserted into a microcatheter, wherein the stentriever comprises an expanded configuration for exerting an outward radial force on the clot, and wherein, when the stentriever is in the expanded configuration, the first expandable clot engagement section has a larger diameter than the proximal flow channel, causing the aspiration to be directed from the first expandable clot engagement section by the first clot engagement membrane and into the proximal flow channel.
 2. The stentriever of claim 1, wherein the first expandable clot engagement section further comprises a first clot inlet capturing the clot.
 3. The stentriever of claim 1, wherein the proximal flow channel comprises: a collapsed configuration to be inserted into the microcatheter, and an expanded configuration wherein the proximal flow channel exerts a radial force on an intermediate catheter, wherein, in the expanded configuration, the proximal flow membrane engages with an inner surface of the intermediate catheter at a proximal seal area to direct aspiration flow.
 4. The stentriever of claim 1, wherein the second expandable clot engagement section comprises a second clot engagement membrane directing the aspiration into the second expandable clot engagement section.
 5. The stentriever of claim 1, wherein the distal engagement section comprises a plurality of distal clot cells capturing clot fragments.
 6. The stentriever of claim 5, wherein the distal engagement section comprises a distal membrane, and wherein the distal membrane comprises distal pores constricting flow of the aspiration into the distal engagement section.
 7. The stentriever of claim 6, wherein: the first expandable clot engagement section further comprises a first clot inlet capturing the clot, and the distal membrane constricts flow from the distal engagement section to the proximal flow channel to create a negative pressure at the first expandable clot engagement section, thereby pulling the clot into the first clot inlet.
 8. A system for removing a clot from a vessel, the system comprising: a stentriever comprising: a shaft extending between a proximal end and a distal end; a first expandable clot engagement section directly connected to and extending from the shaft and comprising a first clot engagement membrane directing an aspiration into the first expandable clot engagement section; a second expandable clot engagement section extending from the shaft and positioned distal to the first expandable clot engagement section; an intermediate flow channel positioned proximal to and adjacent the second expandable clot engagement section; a proximal flow channel positioned proximal to and adjacent the first expandable clot engagement section, the proximal flow channel comprising a proximal flow membrane; and a distal engagement section positioned distal to the first expandable clot engagement section and extending from the shaft; and an intermediate catheter, wherein the stentriever comprises a collapsed configuration to be inserted into a microcatheter, wherein the stentriever comprises an expanded configuration to be expanded in the vessel, wherein, in the expanded configuration, the proximal flow channel exerts a radial force on the intermediate catheter, wherein the proximal flow membrane seals against an inner surface of the intermediate catheter, and wherein, when the stentriever is in the expanded configuration, the first expandable clot engagement section has a larger diameter than the proximal flow channel, causing the aspiration to be directed from the first expandable clot engagement section by the first clot engagement membrane and into the proximal flow channel.
 9. The system of claim 8, wherein the first expandable clot engagement section further comprises a first clot inlet capturing the clot.
 10. The system of claim 8, wherein the second expandable clot engagement section comprises a second clot engagement membrane directing an aspiration into the second expandable clot engagement section.
 11. The system of claim 8, wherein the distal engagement section comprises a plurality of distal pores constricting flow of the aspiration into the distal engagement section.
 12. A stentriever for removing a clot from a vessel, comprising: a shaft extending between a proximal end and a distal end; a first expandable clot engagement section directly connected to and extending from the shaft and comprising a first clot engagement membrane directing an aspiration into the first expandable clot engagement section; a second expandable clot engagement section extending from the shaft, the second expandable clot engagement section being positioned distal to the first expandable clot engagement section, the second expandable clot engagement section comprising a second clot engagement membrane directing the aspiration into the second expandable clot engagement section; a distal engagement section positioned distal to the first expandable clot engagement section and the second expandable clot engagement section and extending from the shaft; and an inner channel extending from a position proximal to and adjacent the first expandable clot engagement section to a position proximate the distal engagement section, the inner channel comprising: a first inner channel membrane positioned along a length of the inner channel proximal to and adjacent the first expandable clot engagement section; and a second inner channel membrane positioned along the length of the inner channel proximal to and adjacent the second expandable clot engagement section, the second inner channel membrane being separated from the first inner channel membrane along a length of the inner channel, wherein the stentriever comprises a collapsed configuration to be inserted into a microcatheter, wherein the stentriever comprises an expanded configuration for exerting an outward radial force on the clot, and wherein, when the stentriever is in the expanded configuration, the first expandable clot engagement section has a larger diameter than the inner channel, causing the aspiration to be directed from the first expandable clot engagement section by the first clot engagement membrane and into the first inner channel membrane.
 13. The stentriever of claim 12, wherein the distal engagement section comprises a plurality of distal clot cells capturing clot fragments.
 14. The stentriever of claim 13, wherein the distal engagement section comprises a distal membrane, and wherein the distal membrane comprises distal pores constricting flow of the aspiration into the distal engagement section. 